优化等待队列的代码

diff --git a/include/wait.h b/include/wait.h
index a3fd1c35ce0d12e737107479dae884319c7c1b7d..f94a0a731cb768c86ed217775623917c05847b08 100644 (file)
--- a/include/wait.h
+++ b/include/wait.h
@@ -22,40 +22,44 @@ typedef struct wait_queue_head {
 
 typedef struct {
     task_t *task;
-    list_head_t task_list;
-} wait_queue_t;
+    list_head_t entry;
+} wait_queue_entry_t;
 
 #define WAIT_QUEUE_HEAD_INITIALIZER(name) \
     { .task_list = LIST_HEAD_INIT((name).task_list) }
 
 #define DECLARE_WAIT_QUEUE_HEAD(name) wait_queue_head_t name = WAIT_QUEUE_HEAD_INITIALIZER(name)
 
-#define WAIT_QUEUE_INITIALIZER(name, tsk) \
-    { .task = tsk, .task_list = LIST_HEAD_INIT((name).task_list) }
+#define WAIT_QUEUE_ENTRY_INITIALIZER(name, tsk) \
+    { .task = tsk, .entry = LIST_HEAD_INIT((name).entry) }
 
-#define DECLARE_WAIT_QUEUE(name, tsk) wait_queue_t name = WAIT_QUEUE_INITIALIZER(name, tsk)
+#define DECLARE_WAIT_QUEUE_ENTRY(name, tsk) wait_queue_entry_t name = WAIT_QUEUE_ENTRY_INITIALIZER(name, tsk)
 
 void init_wait_queue_head(wait_queue_head_t *wqh);
-void add_wait_queue(wait_queue_head_t *head, wait_queue_t *wq);
-void del_wait_queue(wait_queue_head_t *head, wait_queue_t *wq);
+void add_wait_queue(wait_queue_head_t *head, wait_queue_entry_t *wq);
+void del_wait_queue(wait_queue_head_t *head, wait_queue_entry_t *wq);
 
 // prepare_to_wait 不会调用schedule
-void prepare_to_wait(wait_queue_head_t *head, wait_queue_t *wq, unsigned int state);
+void prepare_to_wait(wait_queue_head_t *head, wait_queue_entry_t *wq, unsigned int state);
 
-void __end_wait(wait_queue_t *wq);
+void __end_wait(wait_queue_entry_t *wq);
 
 // 使用这个函数的时候需要注意
 // 设置condition为真的语句和wake_up原子地执行
 void wake_up(wait_queue_head_t *head);
 void __wake_up(wait_queue_head_t *head, int nr);
 
+// 以下wait_event被定义成宏，而不是函数是因为condition
+// condition可能是一个表达式，如果定义成函数，往下传递就直接变成了一个值
+// 如果在某一步这个值变了，并不会反应在这些逻辑判断上
+
 // 只要保证condition设置为真时，它是和wake_up一起原子执行的
 // 那就能保证condition为真是如下__wait_event和wait_event里的if不出问题
 // 也就是不会出现if-break后进程又再次因为其它原因阻塞后，又被wake_up的逻辑
 // 设置为READY状态
 #define __wait_event(head, condition)                  \
     do {                                               \
-        DECLARE_WAIT_QUEUE(__wait, current);           \
+        DECLARE_WAIT_QUEUE_ENTRY(__wait, current);     \
         while (1) {                                    \
             prepare_to_wait(head, &__wait, TASK_WAIT); \
             if ((condition)) {                         \

diff --git a/kernel/wait.c b/kernel/wait.c
index 0ee1d13572a74f721568c2deb60623d5f4a6ebab..6ddb30327cae0324e5702541c09b8f6271fe46ba 100644 (file)
--- a/kernel/wait.c
+++ b/kernel/wait.c
@@ -14,43 +14,43 @@
 
 volatile void init_wait_queue_head(wait_queue_head_t *wqh) { INIT_LIST_HEAD(&wqh->task_list); }
 
-volatile void prepare_to_wait(wait_queue_head_t *head, wait_queue_t *wq, unsigned int state) {
+volatile void prepare_to_wait(wait_queue_head_t *head, wait_queue_entry_t *wqe, unsigned int state) {
     unsigned long flags;
     irq_save(flags);
-    if (list_empty(&wq->task_list)) {
-        list_add_tail(&wq->task_list, &head->task_list);
+    if (list_empty(&wqe->entry)) {
+        list_add_tail(&wqe->entry, &head->task_list);
     }
     set_current_state(state);
     irq_restore(flags);
 }
 
-volatile void __end_wait(wait_queue_t *wq) {
+volatile void __end_wait(wait_queue_entry_t *wqe) {
     set_current_state(TASK_READY);
     unsigned long flags;
     irq_save(flags);
-    list_del_init(&wq->task_list);
+    list_del_init(&wqe->entry);
     irq_restore(flags);
 }
 
-volatile void add_wait_queue(wait_queue_head_t *head, wait_queue_t *wq) {
+volatile void add_wait_queue(wait_queue_head_t *head, wait_queue_entry_t *wqe) {
     unsigned long flags;
     irq_save(flags);
-    list_add_tail(&wq->task_list, &head->task_list);
+    list_add_tail(&wqe->entry, &head->task_list);
     irq_restore(flags);
 }
 
-volatile void del_wait_queue(wait_queue_head_t *head, wait_queue_t *wq) {
+volatile void del_wait_queue(wait_queue_head_t *head, wait_queue_entry_t *wqe) {
     unsigned long flags;
     irq_save(flags);
-    list_del(&wq->task_list);
+    list_del(&wqe->entry);
     irq_restore(flags);
 }
 
 volatile void __wake_up(wait_queue_head_t *head, int nr) {
     unsigned long flags;
-    wait_queue_t *p, *tmp;
+    wait_queue_entry_t *p, *tmp;
     irq_save(flags);
-    list_for_each_entry_safe(p, tmp, &head->task_list, task_list) {
+    list_for_each_entry_safe(p, tmp, &head->task_list, entry) {
         p->task->state = TASK_READY;
         current->reason = "wake_up";
 
@@ -66,11 +66,11 @@ volatile void __wake_up(wait_queue_head_t *head, int nr) {
 
 volatile void wake_up(wait_queue_head_t *head) {
     //
-    __wake_up(head, 1);
+    __wake_up(head, 0);  // wake up all
 }
 
 volatile void wait_on(wait_queue_head_t *head) {
-    DECLARE_WAIT_QUEUE(wait, current);
+    DECLARE_WAIT_QUEUE_ENTRY(wait, current);
 
     unsigned long flags;
     irq_save(flags);
@@ -78,7 +78,7 @@ volatile void wait_on(wait_queue_head_t *head) {
     current->state = TASK_WAIT;
     current->reason = "sleep_on";
 
-    list_add_tail(&wait.task_list, &head->task_list);
+    list_add_tail(&wait.entry, &head->task_list);
 
     irq_restore(flags);